The aim of the proposal is to investigate a variety of information-processing mechanisms in monkeys (Cebus apella) by probing different points of the sequence of information-processing mechanisms that is applied to a stimulus input. All the experiments involve extensive training and testing and employ variants of the delayed matching-to-sample procedure. The mechanisms investigated include stimulus encoding (i.e., the relationship of stimulus identification to the duration of stimulus exposure), selective attention (as revealed by the animal's ability to ignore an irrelevant input and thereby reduce or eliminate the interference normally caused by this stimulus on a second input), and selective retention (i.e., the ability to choose one of two items for preferential retention), which bears on the question of whether animals can actively recycle information in a way that is analogous to human rehearsal. Drawing from some recent developments in human information processing which suggest the existence of two qualitatively different, informaton-processing mechanisms (automatic detection and controlled search), one experiment employs identity and conditional matching to assess whether highly practiced monkeys are capable of performing the two matching tasks with comparable choice response latencies. Such a finding implies that monkeys possess similar information-processing mechanisms and can activate them in parallel.